It is not straightforward to calculate IRR. You can use Excel to find it. However, if you want to calculate without Excel or a financial calculator, you can try different values for i and calculate the present worth for each one of them. Try to find the values of i for which the PW is closest to 0. When you find a positive and a negative PW value, you can use linear interpolation to estimate the value of i. Of course, this is not the actual value, it is an approximation.
